The present invention relates to a travel road detector for detecting a shape of a travel road for a driver's vehicle. Especially, the present invention relates to the travel road detector that is preferable for showing the shape of the travel road with a travel road model parameter.
Japanese Patent Unexamined Publication No. Heisei 6(1994)-020189 describes a road shape measuring instrument for calculating the travel road model parameter with a state estimator such as Kalman filter and the like.